The present invention relates to bracket coupling structures and, more particularly, to a bracket coupling structure useful when fixedly securing an auxiliary unit, such as a sunvisor to be installed inside a vehicle, to a panel.
FIGS. 1 to 3 shows a bracket structure disclosed in Japanese Patent Provisional Publication No. 7-288160. Formed on side surfaces 102a of a bracket 100 formed in a square shape, respectively, are base plate protrusions 101 that protrude at appropriate positions in trailing areas in an insertion direction A and hook portions 102 that protrude at appropriate positions in leading areas in the insertion direction A. An engagement claw segment 103 formed at one end of each base plate protrusion 101 protrudes toward each hook portion 102. Also, formed on side surfaces 100a of the bracket 100 along the insertion direction A is a rotation limit protrusions 104. The that protrude at appropriate positions in trailing areas in an insertion direction A has both ends connected to one end of the base plate protrusion 101 and one end of the hook portion 102 (see FIG. 1).
In the meantime, formed on a peripheral edge of a mounting opening 106 formed in a panel 105 are hook insertion bores 107, which permit the hook portions 102 to be inserted, and a positioning bore 108 (see FIG. 2).
Next, description is made of a sequence of assembling the bracket 100. First, the hook portions 102 of the bracket 100 are positioned in alignment with the hook insertion bores 107 of the mounting opening 106 of the panel 100 and the bracket 100 is inserted to the mounting opening 106 of the panel 105. Subsequently, the bracket 100 continues to be inserted until the base plate protrusions 101 abut the peripheral edge of the mounting opening 106 of the panel 105. Then, the bracket 100 is rotationally operated until the engagement claw segment 103 is brought into mating engagement with the positioning bore 108, and mounting operation is completed. When attempt is made to rotate the bracket to an area far from such a rotating complete position, the rotation limit protrusion 104 is brought into abutting engagement with an end face 107a of the hook insertion bore 107. Thus, excessive rotation of the bracket 100 is avoided.
At the rotating complete position, the bracket 100 is fixed to the panel 105 under a situation in which the peripheral edge of the mounting opening 106 of the panel 105 is sandwiched between the base plate protrusion 101 of the bracket 100 and the hook portions 102 (see FIG. 3).
With the above-described bracket coupling structure, if a thickness T of the panel 105 is less than a deviation dimension D between the base plate protrusion 101 and the hook portions 102 (T≦D), the bracket 100 is allowed to be rotated.